Phenyl-ethynyl terminated imide oligomers can be thermally cured to afford a final resin that possesses excellent mechanical and chemical properties pivotal to high-performance composite applications. The cured phenyl-ethynyl terminated resins possess improved thermo-oxidative stability and processability over thermally cured acetylene-terminated imide oligomer resins. Typical curing temperatures for the neat oligomer are generally near 350xc2x0 C. and the chemical reaction(s) leading to the final resin appears to be multifaceted.
The entire cure process appears to follow a complicated rate law. Some of the most recent studies have suggested that first-order (pseudo) kinetics are followed for the initial 90 percent of the reaction for both an oligomeric material and a bis-phenylethynyl model compound. Other mechanistic studies have demonstrated the complexity of the curing process. In each study performed, there is reasonably good agreement between the kinetic data observed for oligomeric material and their model compound analogs. This point appears to validate the use and study of small molecules to probe both the mechanism and products for at least a majority of the curing reaction(s).
There is a need for a resin that possesses excellent mechanical and chemical properties for high-performance composite application that can be cured at lower temperatures than the phenyl-ethynyl terminated imide materials.
It is an object of the present invention to provide compounds that can be cured at lower temperatures than the phenyl-ethynyl terminated imide materials.
Another object of the present invention is to incorporate polycyclic aromatic rings in aryl-ethynyl end-capping groups. This substitution provides the necessary thermal stability and provides a significant change in stereoelectronics.
It is an object of the present invention to prepare new aryl-ethynyl model compounds and end-capped oligomeric materials.
Further, another object of the present invention is to develop pre-polymers which can be cured at lower temperatures yet produce a final material that possesses the excellent chemical, thermal, and mechanical properties associated with NASA""s thermally cured PETI-5 (Phenyl-Ethynyl Terminated Imide) oligomer.
To these ends, the present invention is directed to the synthesis, thermal curing, and kinetic analysis of a naphthyl-ethynyl imide-model compounds, which cure at a significantly faster rate than the phenyl-ethynyl analog. The present invention is also directed to naphthyl-ethynyl anhydride compounds, anthracenyl-ethynyl imide model compounds, and anthracenyl-ethynyl anhydride compounds.
The present invention includes a compound having the formula: 
wherein R1 is a polycyclicaromatic moiety. R1 may be 9-anthracenyl, 1-napthyl, or 2-napthyl.
The present invention also includes a method for preparing a compound comprising the steps of reacting an anhydride having the formula: 
with a reactive compound where the reactive compound is reactive to the anhydride and where R1 is a polycyclicaromatic moiety. R1 may be selected from the group consisting of 1-napthyl, 2-napthyl, and 9-anthracenyl. The reactive compound may be selected from the group consisting of amines, diamines, triamines, compounds having more than three amino functional groups, phenoxy benzyl diamines, diamines containing aryl substituents, sulfonyl containing compounds, halide containing compounds, ester containing compounds, amide containing compounds, and combinations thereof. The reactive compound may preferably be a thermally stable aromatic bis(amine). Further, the reactive compound may be selected from the group consisting of 
and combinations thereof, where R2 and R3 are alkyl moieties. R2 and R3 may be methyl or other short chain alkyls, C1-C6, and may be the same or different.
The present invention further includes a compound having the formula: 
wherein R1 is a polycyclicaromatic moiety. R1 may be selected from the group consisting of 1-napthyl, 2-napthyl, and 9-anthracenyl. R2 may be an alkyl moiety selected from the group consisting of hydrogen, phenyl, and C1 to C50 alkyl. Further, R2 may be a reactive functional group selected from the group consisting of amino, sulfonyl, halide, ester, and amide functional groups.
Still further, the invention includes a compound having one of the following formulas: 
where R is selected from the group consisting of polymers, oligimers, and reactive moieties. R may be a polymer selected from the group consisting of polyimides, polysulfones, polyaromatics, and polyolefins. Further, R may be a reactive moiety selected from the group consisting of phthalimide and phthalic anhydride.
Further, the invention includes a method for making an polycyclicaromatic-ethynyl capped compound comprising reacting the a polycyclicaromatic-ethynyl compound having one of the following formulas: 
with a reactive compound where R is an anhydride moiety to produce a polycyclicaromatic-ethynyl capped compound. The reactive compound may be selected from the group consisting of amines, diamines, triamines, compounds having more than three amino functional groups, phenoxy benzyl diamines, diamines containing aryl substituents, sulfonyl containing compounds, halide containing compounds, ester containing compounds, amide containing compounds, and combinations thereof. Further, the reactive compound may be a thermally stable aromatic bis(amine).
Still further, the reactive compound may be selected from the group consisting of 
and combination thereof, where R2 and R3 are alkyl moieties. R2 and R3 may be methyl moieties or other short alkyls, C1-C6, and may be the same or different. The anhydride portion of the polycylicaromatic ethynyl compound may include, but is not limited to 3,3xe2x80x2,4,4xe2x80x2-biphenyltetracarboxylic dianhydride, 4,4xe2x80x2-oxydiphthalic anhydride, and combinations thereof. In one embodiment, R may be phthalic anhydride.
The present invention also includes a method for making a polymer comprising:
reacting 
with
Xxe2x80x94R2
to produce 
wherein R1 is a metal anion, X is a halogen, and R2 is a polymer.
Still further the invention also includes a method for making a polymer comprising reacting 
with
Xxe2x80x94R2
to produce 
wherein R1 is a metal anion, X is a halogen, and R2 is a polymer.
Still further, the present invention includes a method for making a polymer comprising:
reacting 
with
Xxe2x80x94R2
to produce 
wherein R is a metal anion, X is a halogen, and R2 is a polymer.
In the cases noted above, the polymer R2 can be a wide variety of different materials including, but not limited to, polyimides, polyamides, polyethers, polysulfones, epoxides, polyalkyls such as polyethylenes, and polycycloaromatics including heteroaromatics.